Robert Alexander (c.1740-1805) was an American planter, lawyer, and Tory political leader during the American Revolution. He was a delegate to the Continental Congress for Maryland in 1776.

Robert was born on his family's estate at Head of Elk in Cecil County, Maryland about 1740. He was educated to the law and admitted to the bar, and practiced in Baltimore. From 1774 to 1776 he attended the Annapolis Convention as a representative of Baltimore County. He also represented Baltimore in the state's Committee of Safety.

On December 9, 1775 the Convention named Alexander one of their delegates to the Continental Congress.He attended sessions starting in January of 1776, and on January 16th the Congress added him to their Secret Committee. Then in April he was added to the Marine Committee.

In August of 1777, after British forces had landed at Head of Elk, he was visited at his home, first by George Washington on the 27th, and then by British General Howe three days later. When the British moved north towards Philadelphia he accompanied them, and was never to return. By the summer if 1778, when Howe abandoned the occupation of Philadelphia, Alexander fled to the British Navy, and made his way to London in 1782.

In 1780, Maryland judged him guilty of high treason, and seized most of his property. His estate became the town Elkton, Maryland, although the wife he had abandoned was allowed to keep the main house that his father had built in 1735. The house still stands, and is located at 323 Hermitage Drive in Elkton. Armstrong died in exile in London, England on November 20, 1805.